Greetings; I have received pretty good help on this forum in the past, so I thought I would try my luck on this one.

On our Pierce engine we have one locking compartment like in image below. The rest of our compartments have a circular non locking mechanism similar to the locking one. My Chief wants me to investigate adding the locking mechanism on some of our other non locking compartments. I'm really not sure where to start looking. Any suggestions?